This invention relates to an absorption machine and, more particularly, to an improved coupled dual loop absorption heat pump/refrigeration machine utilizing two separate complete single effect loops.
In a typical single effect absorption system, water may be the refrigerant and lithium bromide may be the absorbent, and together they are called a solution pair. Some systems employ high temperature solution pairs that are capable of operating at higher generator temperatures to increase efficiency but are precluded from operating at lower evaporator temperatures due to the possibility of freezing and crystallization of the solution pairs, while other chemical systems capable of operating at lower evaporator temperatures could not operate at the higher generator temperatures without chemical stability problems. Consequently, a single effect system is generally a compromise between higher and lower operating temperature conditions in the generator and evaporator.
Well known absorption cycles are mainly of a single effect type comprising a generator for heating a weak or relatively dilute absorbent solution to generate vapor of refrigerant, a condenser for condensing the vapor of refrigerant, an evaporator for evaporating the condensed refrigerant to provide cooling, and an absorber for absorbing the refrigerant vapor of the evaporator into a strong or relatively concentrated absorbent solution. However, the thermal efficiency (coefficient of performance or COP) of a single effect type absorption system is relatively low and ordinarily about 0.6-0.7. With a view toward increasing the thermal efficiency of absorption cycles, double effect type absorption units have been developed in which a second generator is additionally provided in the single effect type absorption unit such that the high temperature vapor of refrigerant generated in a first generator is utilized to heat a second generator.
In general, the double effect type absorption unit comprises a high temperature generator and a low temperature generator whereby the external heat supplied is utilized twice in the high and low temperature generators and so the thermal efficiency increases in comparison with the single effect type system.
An improvement of the double effect type absorption unit has been the dual loop system. The absorption system in U.S. Pat. No. 3,483,710 is a prior art version of a two loop system that combines a higher temperature loop with a lower temperature loop. Although this prior art discloses a high temperature condenser in heat exchange relation with a low temperature generator, it fails to teach the relationship between the other components in both loops.